Pulverized body drying method and apparatus

ABSTRACT

The present invention provides a particulate drying method and drying apparatus, which can disperse particulates in the drying apparatus, prolong the particulate residence time, and improve the drying conditions, while retaining the advantages of conventional flash dryers.

TECHNICAL FIELD The present invention relates to a particulate dryingmethod and drying apparatus, and more particularly to a particulatedrying method and drying apparatus which are used to dry particulates.BACKGROUND ART

Flash dryers and fluidized bed dryers have been the primary devicesknown in the past for drying particulates using heated gas.

Here, a flash dryer is a dryer having a structure in which an ascendingair current is formed by heated gas in a cylindrical straight pipe, theparticulates are fed into the ascending air current, and theparticulates are dried while carried aloft by the ascending air current.

Advantages of such flash dryers are that they have a simple structure,and the particulates are dried at the same time that the air istransported, resulting in high treatment capacity.

On the other hand, the ascending air current is formed only in thestraight pipe in such flash dryers, resulting in less dispersion of theparticulates that are supplied as the material being treated, and whenwet particulates or the like which have formed into lumps are treated, adisperser or beater or the like must be provided near the openingthrough which the treated material is supplied. A resulting problem isthat particulates end up adhering to the mechanical dispersionmechanism, such as the attached disperser or beater.

Furthermore, since the supplied particulate travels along with theascending air current formed in the straight pipe, lengthening thestraight pipe is the only way to prolong the particulate residence timein the straight pipe and to improve the drying conditions (slowing theflow rate of the ascending air current limits the amount treated and thelike), leading to an increase in the size of the equipment.

In addition, since the particulates travel along with the ascending aircurrent in the straight pipe in such devices, often the same heated gasis in contact with the particulates as they travel. There is thus someconcern that the heat exchange between the particulates and the heatedgas as well as the evaporation of moisture from the particulates heatedby this heat exchange reach a critical state soon after contact betweenthe particulates and heated gas, with a dramatic decrease in thesubsequent heat exchange and evaporation. A method that has been adoptedto increase drying efficiency is to provide a curved part in the middleof the straight drying pipe, so as to abruptly alter the direction offlow in the curved part and thus produce instantaneous changes in therate between the particulates and the accompanying heated gas, therebyexchanging the heated gas. However, in this case as well, theparticulate residence time cannot be prolonged, and it is difficult todry the particulate to below the specified moisture. A problem is thusthat wet particulates adhere to the curved part provided in the middleof the drying pipe, in the same manner as when a disperser, beater, orthe like is provided as described above.

Particulates adhering inside the device as described above hinder theoperating stability of the apparatus. In addition, material adheringinside the device sometimes falls off as a result of frequent heatdegeneration and thermal deterioration, becoming mixed in the form ofimpurities with the final product. Such contamination of the finalproduct is a major issue.

The particulate drying action in the flash dryer depends solely on thequantity of heat of the heated gas, so attaching equipment to increasethe amount of hot air, elevate the hot air temperature, and the like inorder to enhance the extent of drying leads to the problems of greatersize and higher running costs.

Fluidized bed dryers which are widely known as apparatuses for dryingparticulates using heated gas in a manner similar to that of flashdryers are apparatuses having a structure in which the container isdivided into two upper and lower chambers by a perforated plate such asa wire netting, the upper chamber is filled with the particulates, andthe heated gas is blown from the lower chamber through the perforatedplate into the upper chamber, causing the particulates to fluidize anddry.

In such a fluidized bed dryer, the drying time can be set as desired,and the particulates can always be kept in contact with fresh heatedgas, resulting in the advantage that the particulates can be dried to anextremely low moisture content. Another advantage is that such fluidizedbed dryers allow the particulates to be uniformly dried.

However, when fluidized bed dryers are used in the case of particulateshaving a high moisture content, the particulate layer is difficult tofluidize, and the particulates are not adequately dispersed. As aresult, dumpling-shaped lumps are produced in the final product, andthere are also problems such as particulate adhesion on the machinewalls.

Thus, when particulates having a high moisture content are dried, theparticulates are generally first dried in a flash dryer such as thatdescribed above to a moisture that will not result in adhesion or lumps,and a fluidized bed dryer is then often used as a finishing dryer.

In view of the problems described above in conventional flash dryers andfluidized bed dryers in which particulates are dried by heated gas, anobject of the present invention is to provide a particulate dryingmethod and drying apparatus which can promote the dispersion of theparticulates in the dryer and prolong the particulate residence time soas to improve the drying conditions while retaining the advantages ofconventional flash dryers.

DISCLOSURE OF THE INVENTION

To achieve the object described above, the present invention is a methodfor drying particulates, wherein a spirally ascending air current isformed by heated gas inside a cylindrical container having an internalspace, the horizontal cross section of which is in the form ofconcentric circles at any height, and particulates are dried by beingdispersed and allowed to float in the spirally ascending air current.

The present invention is also an apparatus for drying particulates,comprising a cylindrical container having an internal space, thehorizontal cross section of which is in the form of concentric circlesat any height, a particulate and heated gas feed pipe which is connectedto the bottom of the cylindrical container, a spiraling mechanism forconverting the heated gas introduced from the feed pipe into a spirallyascending air current inside the cylindrical container, and aparticulate and heated gas discharge pipe which is connected to the topof the cylindrical container.

In the particulate drying method and drying apparatus pertaining to thepresent invention, particulates travel upward from below along with aspirally ascending air current created by heated gas inside thecylindrical container. The particulates are subject to centrifugal forceas well as the upward force of the spirally ascending air current asthey travel, and even particulates in the form of wet lumps are brokendown and are dried in a good dispersed state.

Because the particulates ascend while spiraling inside the cylindricalcontainer in the present invention, the travel distance is far longerthan when they travel along with an air current that merely ascends. Theparticulates are in contact with constantly changing gas as a result ofdifferences in rate due to differences in the friction resistancebetween the internal wall surface of the container and the heated gas incontact with the particulates as they travel, thereby allowing greateramounts of heat to be exchanged and the particulate drying state to beimproved.

In the present invention, the centrifugal force of the spirallyascending air current affecting the particulates is greater the higherthe particulate density due to wetting. As a result, particulates thathave just been introduced and particulates with a greater moisturecontent than others spiral over long periods of time near the internalperipheral wall surface of the cylindrical container, and the residencetime is thus prolonged, resulting in better drying conditions andallowing more uniform drying to be achieved.

Here, as a method for forming a spirally ascending air current in thecylindrical container in the present invention, a heated gas ispreferably introduced in a tangential direction from the entireperiphery of the bottom side wall of the cylindrical container.Alternatively, the heated gas is preferably introduced in a tangentialdirection from the entire periphery of the bottom side wall of thecylindrical container, while heated gas is also introduced in a roughlycircumferential direction concentric with the cylindrical container fromthe entire surface of the bottom wall of the cylindrical container.

As a spiraling mechanism for implementing such a method, the entireperiphery of the bottom side wall of the cylindrical container is madeof a perforated plate in which are formed a plurality of blow holesarranged so that the openings face in a tangential direction of thecylindrical container, the periphery of the perforated plate is enclosedby a container, and the heated gas feed pipe is connected to thiscontainer. Alternatively, the entire periphery of the bottom side wallof the cylindrical container is made of a perforated plate in which areformed a plurality of blow holes arranged so that the openings face in atangential direction of the cylindrical container, the periphery of theperforated plate is enclosed by a container, and the heated gas feedpipe is connected to this container, while the entire surface of thebottom wall of the cylindrical container is made of a perforated platein which are formed a plurality of blow holes arranged so that theopenings face in a roughly circumferential direction concentric with thecylindrical container, the bottom of the perforated plate is enclosed bya container, and the heated gas feed pipe is connected to thiscontainer.

This has the effect of allowing the spirally ascending air current thusformed to prevent the adhesion and accumulation of particulates on theinternal wall surface of the cylindrical container immediately followingtheir introduction in their wettest state, as well as prolonging theresidence of the wet particulates as they spiral at the bottom of thecontainer without ascending.

That is, the spirally ascending air current provides centrifugal forceto the particulates as described above, so there is concern that theparticulates will be forced against the internal wall surface of thecylindrical container, where they will adhere and accumulate. Thisphenomenon is most pronounced at the bottom of the cylindrical containerwhere the particulates being treated are introduced. When the heated gasis introduced in a tangential direction from the entire periphery of thebottom side wall at the bottom of the cylindrical container where thereis most concern over the adhesion and accumulation of particulates, orthe heated gas is introduced in a tangential direction from the entireperiphery of the bottom side wall of the cylindrical container whileheated gas is also introduced in a roughly circumferential directionconcentric with the cylindrical container from the entire surface of thebottom wall of the cylindrical container, a spirally ascending aircurrent is formed in the cylindrical container, allowing theparticulates to spiral therein, and a so-called air carton is formed bythe heated gas near the bottom side wall of the cylindrical container ornear the bottom side wall and the bottom wall. This air carton canprevent the particulates from coming into direct contact with the innerwall surface of the cylindrical container so as to prevent them fromadhering and accumulating there. Heated gas which is blown in atangential direction from the entire periphery of the bottom side wallforms, in that location, a rapidly spiraling air current, referred to asan air ring, which is wider in the center than at the side wall, andthis air ring causes wet particulates to remain while circling at thebottom of the container without ascending, thereby promoting particulatedrying.

In the present invention, the cylindrical container is preferably heatedfrom the outer peripheral surface. The structure for heating thecylindrical container from the outer peripheral surface is preferablyconstructed in such a way that the outer peripheral wall surface of thecylindrical container is enclosed by a jacket, and a heat medium issupplied into the space formed between the jacket and the outerperipheral wall surface of the cylindrical container.

In the present invention, the particulates described above are subjectto the centrifugal force of the spirally ascending air current formed inthe cylindrical container, and they travel while forced against theinner peripheral wall surface of the cylindrical container. This isdesirable because, when the cylindrical container is heated, theparticulates are effectively dried by means of heat transfer byconduction from the cylindrical container.

In the present invention, the cylindrical container is preferablyconstructed so as to be dividable at suitable locations in the axialdirection. As a structure for implementing this construction, thecylindrical container is divided at any location in the axial direction,flanges are provided at the open end surface of the divided parts, andthe flanges are detachably joined face-to-face with a clamp or the like.

This is desirable because, when the cylindrical container is dividablyconstructed in the manner described above, the apparatus is easier toassemble and disassemble, the interior of the container is easy toclean, and the length of the container can be shortened or converselylengthened as needed.

In the present invention, an air current spiraling at a high speed, thatis, an air ring, in the same direction as the spirally ascending aircurrent, is preferably formed in a location at any height inside thecylindrical container. To form this air ring, the entire periphery ofthe side wall at any location of the cylindrical container is preferablymade of a perforated plate having a plurality of blow holes arranged sothat the openings face in the same direction as the spiraling directionof the spirally ascending air current formed in the cylindricalcontainer, the periphery of the perforated plate is enclosed by acontainer, and the heated gas feed pipe is connected to this container,thereby forming an air ring at that location.

This is desirable because, when such an air ring is located in themiddle of the cylindrical container, the air ring keeps in that locationthe particulates which have traveled up along the inner wall of thecylindrical container while spiraling up along with the spirallyascending air current, so that the particulates kept there can havesufficient residence time while in actual contact with fresh heated gasin that location, resulting in better drying conditions.

In the present invention, the diameter of the spiral of the spirallyascending air current formed in the cylindrical container is preferablywider in the middle of the ascent. To thus widen the spiral diameter,the cylindrical container having a horizontal cross section in the formof concentric circles at any height is preferably a cylindricalcontainer in which the horizontal cross section is in the form ofconcentric circles that are wider in the middle in the axial directionthan the other parts.

This is desirable because, when such a wider part is located in themiddle, the rate at which the spirally ascending air current ascends issuddenly lowered in the wider part, and the particulates ascend at alower rate, allowing the particulate residence time in the container tobe prolonged. In addition, the heated gas and particulates are forciblyseparated by the differences in centrifugal force in the wider part,allowing the particulates to come into actual contact with fresh heatedgas. As a result, when the wider part is located in the middle, thedrying conditions for the particulates are better, just as they are whenan air ring is provided.

When the spiral diameter of the spirally ascending air current formed inthe cylindrical container is wider in the middle of the ascent, thecylindrical container is preferably heated from the outer peripheralsurface with a structure similar to that described above at the locationwhere the spiral diameter is wider, or heated gas is preferably alsointroduced in the same direction as the spiraling direction of thespirally ascending air current with a structure similar to thatdescribed above at the location where the spiral diameter is wider,because the wider part is where the particulates are kept as describedabove, making the particulates susceptible to the heat transfer byconduction from the cylindrical container, and the particulates can comeinto contact with the low humidity heated gas that has been introduced,further improving the drying conditions.

When an air ring is formed at a location at any height in thecylindrical container, the outer peripheral surface of the cylindricalcontainer is preferably heated with a structure similar to thatdescribed above at a location below where the air ring has been formed,for the same reasons as described above.

In the present invention, when the particulates being dried do notadhere very much, a heated gas may be introduced from a tangentialdirection at the bottom side wall of the cylindrical container so as toform the spirally ascending air current in the cylindrical container,and the particulates and heated gas may be simultaneously introducedfrom a tangential direction at the bottom side wall of the cylindricalcontainer. In this case, however, the spiral diameter of the spirallyascending air current formed in the cylindrical container is preferablywider in the middle of the ascent, or an air ring is formed at alocation at any height inside the cylindrical container, or another suchmeans is employed, so as to increase the drying efficiency.

It is preferable to use the dryer pertaining to the present inventionwith a conventional flash dryer, that is, the outlet side end of thedrying pipe of the flash container is connected in a tangentialdirection at the bottom side wall of the cylindrical container, so as toform the spirally ascending air current inside the cylindricalcontainer, and the particulates that have been dried by the flash dryerare preferably then dried again by the drying method and dryingapparatus pertaining to the present invention.

This is preferable because more efficient drying is possible, such as alower optimal particulate moisture at the heated gas temperature andamount of air used in flash dryers, greater treated quantities when theoptimal moisture is the same, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross section of a first embodiment of theapparatus of the present invention;

FIG. 2 is an enlarged cross section of the portion along line A--A inFIG. 1;

FIG. 3 depicts the apparatus of the present invention along with deviceswhich are needed before and after it;

FIG. 4 is an enlarged cross section of the perforated plate used in theapparatus pertaining to the present invention;

FIG. 5 is an enlarged cross section of another perforated plate used inthe apparatus pertaining to the present invention;

FIG. 6 is a plan of a perforated plate used in the apparatus pertainingto the present invention;

FIG. 7 is a plan of another perforated plate used in the apparatuspertaining to the present invention;

FIG. 8 is an enlarged cross section of another structure for the partalong line A--A in FIG. 1;

FIG. 9 is a vertical cross section of a second embodiment of theapparatus of the present invention;

FIG. 10 depicts the second embodiment of the apparatus of the presentinvention along with devices that are needed before and after it;

FIG. 11 is a vertical cross section of a third embodiment of theapparatus pertaining to the present invention;

FIG. 12 is an enlarged cross section of the part along line B--B in FIG.11;

FIG. 13 depicts the third embodiment of the apparatus pertaining to thepresent invention along with the devices that are needed before andafter it;

FIG. 14 is a vertical cross section of a fourth embodiment of theapparatus pertaining to the present invention;

FIG. 15 is a vertical cross section of a fifth embodiment of theapparatus pertaining to the present invention;

FIG. 16 is a vertical cross section of a sixth embodiment of theapparatus pertaining to the present invention;

FIG. 17 is an enlarged cross section of the part along line C--C in FIG.16;

FIG. 18 depicts a seventh embodiment of the apparatus pertaining to thepresent invention along with the devices that are needed before andafter it; and

FIG. 19 depicts an eighth embodiment of the apparatus pertaining to thepresent invention along with the devices that are needed before andafter it.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention are described below with referenceto the figures.

FIGS. 1 through 3 depict a first embodiment of the present invention. InFIGS. 1 through 3, 1 is a cylindrical container having an internal hole2, the horizontal cross section of which is in the form of concentriccircles at any height. The cylindrical container 1 is formed longer inthe axial direction than in the diameter direction, and both ends areclosed. The container is set up with the axis facing in theperpendicular direction. The cylindrical container 1 is not limited tothe cylindrical configuration shown in the figure, however, and may alsobe in the form of a truncated cone with the diameter widening ornarrowing toward the bottom, or the container may be wider in the middlein the heightwise direction, as in the shape of a beer keg.

A perforated plate 3 is arranged at the bottom of the cylindricalcontainer 1. The internal space 2 of the cylindrical container 1 isdivided by the perforated plate 3 into a lower hot air chamber 2a andupper drying chamber 2b. The perforated plate 3 is not limited to theflat plate depicted in the figure, however, and may also be formed inthe shape of a cone with an upwardly or downwardly protruding center,for example. In particular, a guide tube (not shown in figure) forintermittently or continuously discharging particulates that haveaccumulated and have not been entrained by the air current may beconnected to the lowermost part when the perforated plate is in the formof a cone with an upwardly or downwardly protruding center.

A heated gas feed pipe 4 is connected to the side surface (or bottomsurface) of the hot air chamber 2a formed at the bottom of thecylindrical container 1. As shown in FIG. 3, air which has been cleanedby an air filter 5 and which has been heated by an air heater 6 issupplied through the feed pipe 4 into the hot air chamber 2a by theblowing action of a supply blower 7.

In FIG. 3, 8 is a heat medium (such as water vapor) feed pipe forsupplying a heat medium to the air heater 6. 9 is a temperature controldevice provided at the feed pipe 8, and is constructed in such a way asto control the opening and closing of a valve 12 provided in the feedpipe 8 in response to the temperature of the heat medium detected by atemperature detector 11 provided in the middle of the heated gas feedpipe 10.

The bottom surface 13 of the hot air chamber 2a does not need to behorizontal, and may be in the form of a cone with a downwardly orupwardly protruding center or may be inclined in one direction as shownin the figure. This is particularly desirable because, when the bottomsurface 13 is inclined in one direction, as shown in the figure, nowashing water accumulates at the bottom surface 13 when the container 1is washed, and all the washing water can be discharged through thedischarge pipe 14 provided at the lowermost part. When a hand hole 15 isprovided as shown in FIG. 3 at the side surface of the hot air camber2a, the hot air chamber 2a is more easily inspected, cleaned, and thelike.

A plurality of blow holes 16 are formed in the perforated plate 3dividing the bottom part of the cylindrical container 1, so that theheated gas introduced from the hot air chamber 2a through the perforatedplate 3 to the drying chamber 2b produces a spirally ascending aircurrent. As shown in FIG. 4, for example, the configuration of the blowholes 16 is such that the top of the hole 17 is enclosed by aroof-shaped protrusion 19 so that the opening 18 of the hole 17 faces ina side direction that is roughly parallel to the flat surface of theflat plate. A plurality of blow holes 16 having this configuration arearranged so that the openings 18 in the quarter circles shown in FIG. 2face in roughly the circumferential direction concentric with thecylindrical container 1, and the openings 18 within thecircumferentially adjoining quarter circles are set off 90° from eachother. The blow holes 16 formed in the perforated plate 3 may be shapedwith the roof-shaped protrusions 19 facing downward as shown in FIG. 5,and the blow holes may be in the form of long so-called slits. Thedisposition of the blow holes 16 may also be such that the openings 18face in the same direction within the range of the precisely dividedangles shown in FIG. 2. As shown in FIGS. 6 or 7, moreover, thearrangement may also be such that the openings 18 of the blow holes 16are facing roughly at right angles to the radial direction. In FIGS. 4and 5, the upper side of the perforated plate 3 is the drying chamber2b, and the lower side is the hot air chamber 2a. In these figures, theheated gas passes from the hot air chamber 2a through the holes 17 fromthe lower right to the upper left, flows along the upper surface of theperforated plate 3 from the right side to the left side, and isintroduced into the drying chamber 2b.

The inner peripheral wall surface of the container 1 located directlyabove the perforated plate 3 is made of a perforated plate 20 in whichthe same type of blow holes 16 as those shown in FIG. 4 (or 5) (theseblow holes 16 may also be blow holes in the form of so-called long slitsin the same manner as the blow holes 16 of the perforated plate 3 above)are formed along the entire periphery at a constant breadth. Theplurality of blow holes 16 of the perforated plate 20 are arranged sothat the openings 18 of the blow holes 16 are facing systematically in atangential direction of the container as shown in FIG. 2. The heated gassupplied through the perforated plate 20 into the drying chamber 2b thusalso forms a spiraling air current in roughly the horizontal directionin the same direction as the spiraling air current formed in the dryingchamber 2b by the porous plate 3.

The blow holes 16 of the bottom part of the perforated plate 20 arepreferably as near as possible to the perforated plate 3. The junctionbetween the perforated plate 20 and the perforated plate 3 need not beat right angles as shown in the figure, and is preferably constructed insuch a way that a suitable curvature or angle is provided in the corner,the heated gas blow holes 16 are also arranged in the corner, and theheated gas is blown through. This is because particulates can beprevented from adhering to and accumulating in the corner when such acorner is provided. The axial breadth of the perforated plate 20 is wideenough to reach the top of the connecting part of the particulate feedpipe 23 described below.

The entire periphery and breadth of the perforated plate 20 constitutingthe inner peripheral wall surface of the bottom of the cylindricalcontainer 1 is completely enclosed by a container 21. A hot air chamber21a is formed between this container 21 and the perforated plate 20. Aheated gas feed pipe 22 is connected to the side surface of the hot airchamber 21a, and air which has been cleaned by an air filter 5 andheated by an air heater 6 in the same manner as the hot air chamber 2ashown in FIG. 3 is supplied through the feed pipe 22 by the blowingaction of a supply blower 7.

In FIG. 2, the heated gas feed pipe 22 is connected at right angles tothe wall surface of the container 21, but, as shown in FIG. 8, the feedpipe 22 is preferably connected to the wall surface of the container 21from the direction in which the openings 18 of the blow holes of theperforated plate 20 are facing, that is, a roughly tangential directionin the same rotating direction as the spirally ascending air currentformed in the cylindrical container 1.

When the feed pipe 22 is connected in the direction at right angles tothe wall surface of the container 21 as shown in FIG. 2, the heated gasintroduced through the feed pipe 22 strikes against the perforated plate20 and is thus divided to the left and right, flowing into the hot airchamber 21a. The heated gas flowing into the hot air chamber 21a fromthe same rotating direction as the spirally ascending air current (leftside viewed from the feed pipe 22 side in the figure) is vigorouslyblown through the blow holes 16 of the perforated plate 20 into thedrying chamber 2b. However, heated gas flowing in from the directionrotating opposite the spirally ascending air current (left side viewedfrom the feed pipe 22 side in the figure) is opposite the direction ofthe openings 18, slowing down the speed of this heated gas, so it is notreadily blown through the blow holes 16 into the drying chamber 2b. As aresult, the amount of heated gas supplied from the blow holes 16 intothe drying chamber 2b is not uniform, and the flow rate of the spirallyascending air current formed in the drying chamber 2b is not uniform.

In addition to the above, the heated gas flowing in from the directionrotating opposite the spirally ascending air current (left side viewedfrom the feed pipe 22 side in the figure) produces negative pressure atthe part of the perforated plate 20 near the connecting part of the feedpipe 22, resulting in the phenomenon whereby gas inside the dryingchamber 2b is suctioned in reverse through the blow holes 16 to the hotair chamber 21a side due to an ejector effect. The suctioned gas resultsin the so-called particle leakage phenomenon, wherein particulates inthe drying chamber 2b are blown out, albeit in small amounts, to the hotair chamber side 21a. The particulates blown out to the hot air chamber21a side travel into the hot air chamber 21a with the heated gas that iscontinuously supplied, and are kept in locations where this heated gascollides (in FIG. 2, the connecting part of the particulate feed pipe 23described below, since the heated gas flowing in from the right side isblown out to the drying chamber 2b) with heated gas flowing in from thedirection rotating in the same direction as the spirally ascending aircurrent. The particulates trapped in this manner have no place to go,and the amount increases over time. Between the parts of the perforatedplate 20 where the particulates are blown out and the parts where theparticulates remain, even when no particulates are blown out,particulates in the drying chamber 2b occasionally circulate to the hotair chamber 21a side and adhere to the outer peripheral wall surface ofthe perforated plate 20. Particulates which thus adhere to andaccumulate on the outer peripheral wall surface parts of the perforatedplate 20 clog the blow holes 16 formed in the perforated plate 20.

In contrast, in cases where the feed pipe 22 is connected to the wallsurface of the container 21 from roughly the tangential direction in thesame rotating direction as the spirally ascending air current formed inthe cylindrical container 1, as shown in FIG. 8, the heated gasintroduced from the feed pipe 22 flows in a constant direction (the samerotating direction as the spirally ascending air current) into the hotair chamber 21a, and is uniformly and smoothly blown from the openings18 of the blow holes 16 into the drying chamber 2b. No particle leakagethus occurs.

For the same reasons as those described above, the feed pipe 4 throughwhich heated gas is fed into the hot air chamber 2a is preferablyconnected to the side surface of the hot air chamber 2a from a roughlytangential direction in the same rotating direction as the spirallyascending air current formed in the cylindrical container 1, in the samemanner as in the case of the feed pipe 22 described above.

A feed pipe 23 through which the wet particulates being treated aresupplied into the drying chamber 2b is connected to the side surface ofthe container 21 through the perforated plate 20 on the inside and thecontainer 21, as shown in FIG. 1. A particulate constant rate feeder 24such as the screw conveyor depicted in FIG. 3 is connected to the feedpipe 23. The particulate constant rate feeder 24 is preferably a feederwhich is air-tight but in which the machine pressure balance ismaintained by the supply blower 7 described above and the dischargeblower 28 described below, so as to prevent the heated gas inside thedrying chamber 2b from being blown out from the feeder 24 through thefeed pipe 23 to the outside or conversely the outside air from beingsuctioned in from the feeder 24 into the drying chamber 2b.

A discharge pipe 25 is connected in a tangential direction in the samerotating direction as the spirally ascending air current formed insidethe cylindrical container 1 to the side wall at the top of thecylindrical container 1. The discharge pipe 25 is connected to adischarge blower 28 through a cyclone or other such particulateseparator 26 and piping 27 as shown in FIG. 3.

The discharge pipe 25 need not necessarily be connected from atangential direction to the cylindrical container 1 as described above,and may be connected from above in the central axial direction of thecontainer 1 to the top (top end surface) of the container 1. In thecylindrical container 1 described above, where D is the diameter, and Lis the length of the drying chamber 2b from the perforated plate 3 tothe top end surface, L is preferably 2D to 10D, and even more preferably3D to 6D.

When the outer peripheral wall surface of the drying chamber 2b isenclosed by a jacket, as shown in FIG. 1, and a heat medium such as hotwater or heated steam is continuously supplied through a pipe 31 intothe space 30 formed between the jacket 29 and outer peripheral wallsurface and discharged through a pipe 32 (the above is for cases of hotwater, whereas in the case of heated steam, the up and down directionsof the supply and discharge pipes are reversed), particulates can bedried by means of the heat transfer by conduction of the heat medium inthe wall surface of the drying chamber 2b, and at least the wall surfaceof the drying chamber 2b can be heated.

As shown in FIG. 3, furthermore, the cylindrical container 1 is dividedinto a drying chamber 2b and a hot air chamber 2a directly below theperforated plate 3, the drying chamber 2b is also divided directly abovethe perforated plate 20 and directly below the connecting part of thedischarge pipe 25, and the drying chamber 2b therebetween may also bedivided into roughly equal lengths in the axial direction as needed. Theapparatus is easily assembled and disassembled when the container isconstructed of units comprising divided parts enclosed by a jacket 29,flanges are provided at the open end surfaces of the units, and theflanges are detachably joined face-to-face with a clamp or the like. Theinterior of the container can also be completely cleaned. The length ofthe drying chamber 2b can also be shortened or conversely lengthened asneeded.

A method for drying particulates using the apparatus of the presentinvention constructed in the foregoing manner is described next.

First, air that has been cleaned by the air filter 5 and heated by theair heater 6 is supplied by the operation of a supply blower 7 throughfeed pipes 4 and 22 to the hot air chambers 2a and 21a. The same amountof heated gas as that supplied to the hot air chambers 2a and 21a issuctioned and discharged from the drying chamber 2b through thedischarge pipe 25, particulate separator 26, and piping 27.

Hot water heated to a constant temperature is continuously suppliedthrough the pipe 31 into the space formed between the outer peripheralwall surface of the drying chamber 2b and the jacket 29 to heat the wallsurface of the drying room 2b.

The heated gas supplied to the hot air chamber 2a is blown from the blowholes 16 of the perforated plate 3 into the drying chamber 2b to form arapid spirally ascending air current on the perforated plate 3.Meanwhile, the heated gas supplied to the hot air chamber 21a is blownfrom the blow holes 16 of the perforated plate 20 into the dryingchamber 2b, forming a rapidly spiraling air current in the peripheraldirection along the perforated plate 20. Both heated gases ascend whilespiraling along the wall surface of the drying chamber 2b and aredischarged outside the system from the discharge pipe 25 through theparticulate separator 26 and piping 27 from the discharge blower 28.

The amount and proportion of the heated gases blown from the perforatedplate 3 and perforated plate 20 into the drying chamber 2b can becontrolled by valves 33 and 34 located in the middle of the heated gasfeed tubes 4 and 22 and the valve 35 located in the middle of the piping27.

After the temperature inside the drying chamber 2b has reached theprescribed level and the spirally ascending air current created by theheated gas has stabilized, the constant rate feeder 24 is actuated, andparticulates are supplied in a constant amount from the particulate feedpipe 23 into the drying chamber 2b.

The particulates supplied into the drying chamber 2b are instantaneouslydispersed forcibly by the heated gas rapidly spiraling in the peripheraldirection along the perforated plate 20, and are borne by the spiralingascending air current formed by the heated gas inside the drying chamber2b.

At this time, the particulates that have been supplied spiral vigorouslyalong the perforated plate 20 under the centrifugal force of thespiraling ascending air current. However, because the heated gas iscontinuously blown from the perforated plate 20, the particulates arenot forced against the perforated plate 20. As a result, theparticulates do not adhere to and accumulate on the inner peripheralwall surface (perforated plate 20) of the container 1, even when theparticulates have a high moisture content immediately after beingsupplied into the drying chamber 2b and are thus in a state most likelyto adhere to the inner peripheral wall surface. If by some chance theparticulates do come into contact with the wall surface and adherethereon, since heated gas is continuously being blown in parallel to thesurface of the perforated plate 20 from the blow holes 16 of theperforated plate, the particulates can be blown off immediately afteradhering thereon. Since heated gas is similarly blown out continuouslyfrom the perforated plate 3 serving as the bottom wall of the dryingchamber 2b, no particulates adhere to and accumulate on the bottom wallof the drying chamber 2b.

While they are wet and have high density, the particulates borne on thespirally ascending air current remain circling in virtually the samehorizontal plane because of the strong centrifugal force from thespirally ascending air current and the action of gravity, allowing theparticulates to be dried by the thermal energy of the heated gas.

At this time, the surface area, configuration, and opening ratio of theopenings 18 of the blow holes 16 of the perforated plate 20 are constantin all locations, and even though the flow rate of the heated gas blownfrom all blow holes 16 is uniform, the flow rate of the spirallyascending air current near the perforated plate 20 gradually builds upin the upward direction, increasing toward the upper side in the axialdirection. Due to the resistance caused by the resident particulates, itis difficult for the heated gas to be blown out from the blow holes 16of the perforated plate 20 (same peripheral surface of parts whereparticulate feed pipe 23 is connected) located in the bottom part wherethe wet, high density particulates are trapped while circulating. As aresult, the flow rate of the heated gas blown from the blow holes 16 atthe top is actually greater than this, and the blowing rate is faster. Aso-called air ring is formed in this part, and this air ring has thesame effect on particulates supplied into the drying chamber 2b as if apartitioning ring with a circular opening in the center were attachedfrom the side wall of the drying chamber 2b, thereby preventing theparticulates from traveling upward along with the ascending air current.

Because of the decrease in centrifugal force produced from the spirallyascending air current and the action of gravity, and because of thecontinuous supply of particulates from the particulate feed pipe 23, theparticulates which have been supplied earlier and have become lighterupon being dried travel in the direction of the center and travel upwardinside the drying chamber 2b along with the ascending air current whilespiraling through the opening of the air ring created by the spiralingascending air current. The particulates are discharged through thedischarge pipe 25, separated from the air current by the particulateseparator 26, and recovered in the form of dry particulates.

Although the perforated plate 20 cannot be clearly delineated into apart where the particulates are prevented from coming into directcontact with the inner peripheral wall surface of the cylindricalcontainer 1 (adhesion prevention zones) and a part where theparticulates are prevented from traveling upward (travel preventionzones), if the perforated plate is divided into these two zones for thesake of simplicity, the perforated plate serving as the travelprevention zone need not necessarily be connected directly over theperforated plate serving as the adhesion prevention zone. That is, theremay be parts where no perforated plate exists at a constant width in theaxial direction between the two zones of the cylindrical container 1.

The particulates which are treated by the foregoing drying method may beused with various types of inert gases, such as nitrogen, as the heatedgas instead of air in cases where various types of organic solvents areused or in cases where there is a danger of ignition or explosion due tothe physical properties or the like of the particulates. In such cases,the particulates may be dried by connecting the piping at the outlet ofthe discharge blower 28, for example, via a solvent recovery device (notshown in figure) to the air heater 6, and by forming a closed circuit todisplace the interior of the closed circuit with an inert gas.

A second embodiment of the device pertaining to the present invention isdescribed below with reference to FIGS. 9 and 10.

Parts which are the same as those in the apparatus in the firstembodiment of the apparatus pertaining to the present invention aredesignated by the same symbols and will not be further described.

As shown in FIG. 9, the apparatus in the second embodiment of thepresent invention is an apparatus in which a perforated plate 40 similarto that described above (a perforated plate in which the same type ofblow holes 16 as in FIGS. 4 and 5 or long slits are formed, and theopenings 18 of the blow holes 16 are arranged systematically facing in atangential direction of the container 1 in the same manner as in thecase of the perforated plate 20) is provided along the entire peripheryat a constant width on a part of the inner peripheral wall surface ofthe drying chamber 2b located below the discharge pipe 25. The entirebreadth of the entire periphery of the perforated plate 40 is completelyenclosed by a container 41 in the same manner as described above, and ahot air chamber 41a is formed between the container 41 and perforatedplate 40. The structure of the device is thus such that a heated gasfeed pipe 42 is connected to the side surface of the hot air chamber41a. The other parts are the same as the apparatus in the firstembodiment of the present invention described above.

The heated gas feed pipe 42 described above is also preferably connectedto the container 41 from a roughly tangential direction in the samerotating direction as the spirally ascending air current formed in thecylindrical container 1 in the same manner as in the heated gas feedpipes 4 and 22 described above.

In the apparatus described above, the particulates that are suppliedthrough the feed pipe 23 into the drying chamber 2b are forciblydispersed and dried by the heated gas rapidly spiraling in theperipheral direction along the perforated plate 20 in the same manner asin the apparatus in the first embodiment described above. While theparticulates are wet and have high density, they remain circling invirtually the same horizontal plane because of the strong centrifugalforce from the spirally ascending air current and the action of gravity,allowing the particulates to be dried by the thermal energy of theheated gas. Because of the decrease in centrifugal force produced fromthe spirally ascending air current and the action of gravity, andbecause of the continuous supply of particulates from the particulatefeed pipe 23, the particulates which subsequently dry and become lightertravel in the direction of the center and travel while spiraling upward.The particulates thus reach the location where the perforated plate 40described above has been provided.

At the location where the perforated plate 40 has been provided, heatedgas is introduced through the feed pipe 42 into the hot air chamber 41a,and heated gas is blown from the perforated plate 40 into the dryingchamber 2b. A rapidly spiraling air current, that is, the air ringdescribed above, is thus formed in the peripheral direction along theperforated plate 40 in this part. The air ring has the effect ofblocking particulates that have traveled spiraling upward along theinner wall of the cylindrical container 1. The particulates which havebeen prevented from traveling upward remain circling at the bottom ofthe air ring and are effectively dried by means of the thermal energy ofthe heated gas and by means of the heat transfer by conduction from theheat medium when a heat medium is supplied into the space 30 between theouter peripheral wall surface. Because of the decrease in centrifugalforce produced from the spirally ascending air current, the particulateswhich subsequently dry and become lighter again travel in the directionof the center and are discharged from the discharge pipe 25 along withthe spirally ascending air current through the opening formed in thecenter of the air ring. The particulates discharged from the dischargepipe 25 are separated from the air current by the particulate separator26 and are recovered in the form of thoroughly dried particulates.

In the apparatus described above, heated gas blown from the perforatedplate 40 is controlled (the valve 43 provided in the middle of the feedpipe 42 shown in FIG. 10 is opened or closed, and the flow rate isadjusted), allowing the particulate behavior (residence time) to becontrolled, that is, allowing the particulates to be kept in thatlocation, to be released (along with the ascending air current), and thelike. Two or more structures constituting the air ring can be set up atintervals in the central axial direction, and can be operated andcontrolled in the same manner as above.

A third embodiment of the device pertaining to the present invention isdescribed below with reference to FIGS. 11 through 13.

In this embodiment, parts which are the same as those in the apparatusin the first embodiment of the apparatus pertaining to the presentinvention described above are designated by the same symbols and willnot be further described.

The apparatus in the third embodiment is one in which part of the dryingchamber 2b located under the discharge pipe 25 described above is formedinto a drying chamber such that the horizontal cross section is in theform of concentric circles that are wider than the other parts(hereinafter, widened drying chamber 50). The other parts are the sameas those of the first embodiment of the apparatus pertaining to thepresent invention described above.

Specifically, the widened drying chamber 50 described above has astructure in which a cylindrical member 51 having a large insidediameter is connected via truncated cone members 52 and 53 to a part ofthe cylindrical container 1 as shown in the figures, for example.

This apparatus preferably has a structure in which the outer peripheralwall surface of the widened drying chamber 50 described above isenclosed by a jacket 54, and a heat medium such as hot water or heatedsteam is supplied continuously through a pipe 56 into the space formedbetween the jacket 54 and outer peripheral wall surface, and isdischarged from a pipe 57 (the above is for cases of hot water, whereasin the case of heated steam, the up and down directions of the supplyand discharge pipes are reversed), allowing the particulate dryingconditions to be even further improved.

As shown in FIG. 13, the cylindrical container 1 is divided into upperand lower parts of the widened drying chamber 50 described above, andthe parts of the other drying chamber 2b are also divided into virtuallythe same lengths in the axial direction as needed. When composed ofunits with flanges provided at the open end surfaces of the dividedparts, the parts can be readily joined with clamps or the like in thesame manner as the apparatus in the first embodiment, affording the sameeffects as that apparatus.

The widened drying chamber 50 can be readily replaced, depending on theparticulate properties, the target moisture content, and the like, bypreparing a plurality of units in which the cylindrical member 51comprising the widened drying chamber 50 has varying inside diameters. Aplurality of units having a widened drying chamber 50 can be connectedto prolong the particulate residence time.

The section area of the widened drying chamber 50 described above shouldbe 1.1 to 3.0 times, and preferably 1.1 to 2.0 times, greater than thatof the other drying chamber 2b.

This is because a drying chamber 50 with a section area less than 1.1times greater has little effect in prolonging the particulate residencetime. When the drying chamber 50 is more than 3 times greater, on theother hand, the flow rate of the spirally ascending air current in thewidened drying chamber 50 is markedly slower, depending on the flow rate(flow speed) of the heated gas being supplied, and neither sufficientcentrifugal force for causing the particulates to travel in a spiral norascending force for causing the particulates to travel upward can beprovided.

In the apparatus described above, the rate at which the spirallyascending air current ascends in the widened drying chamber 50 ismarkedly lower, allowing the particulates to remain rotating once againin virtually the same horizontal plane similar to the effects obtainedwhen an air ring is formed in the apparatus in the second embodimentdescribed above. The particulates thus staying are effectively dried bymeans of the thermal energy of the heated gas and by means of the heattransfer by conduction from the heat medium when a heat medium issupplied into the space 55 between the outer peripheral wall surface.Because of the decrease in centrifugal force produced from the spirallyascending air current, the particulates which dry and become lighteragain travel in the direction of the center and are discharged from thedischarge pipe 25 along with the spirally ascending air current. Theparticulates discharged from the discharge pipe 25 are separated fromthe air current by the particulate separator 26 and are recovered in theform of thoroughly dried particulates.

A fourth embodiment of the device pertaining to the present invention isdescribed below with reference to FIG. 14. In this embodiment, partswhich are the same as those in the apparatus in the first and thirdembodiments of the apparatus pertaining to the present inventiondescribed above are designated by the same symbols and will not befurther described.

The apparatus in the fourth embodiment is one in which a mechanism 60for blowing heated gas (low humidity secondary air) is formed at thebottom of the widened drying chamber 50 of the apparatus in the thirdembodiment described above. The other parts are the same as those in theapparatus in the third embodiment of the present invention.

Specifically, as shown in FIG. 14, the apparatus has a structure inwhich the same type of perforated plate 61 as that described above (aperforated plate in which the same type of blow holes 16 as in FIGS. 4and 5 or long slits are formed, and the openings 18 of the blow holes 16are arranged systematically facing in a tangential direction of thecontainer 1 in the same manner as in the case of the perforated plate20) is provided at a constant width along part or all of the sidesurface of the bottom of the widened drying chamber 50 and the partconnecting the bottom part and the drying chamber 2b located under it.The entire breadth of the entire periphery of the perforated plate 61 iscompletely enclosed by a container 62 in the same manner as describedabove, and a hot air chamber 62a (air current reservoir) is formedbetween the container 62 and perforated plate 61. The structure of thedevice is thus such that a heated gas feed pipe 63 is connected to theside surface of the hot air chamber 62a.

The heated gas feed pipe 63 described above is also preferably connectedto the container 62 from a roughly tangential direction in the samerotating direction as the spirally ascending air current formed in thecylindrical container 1 in the same manner as in the heated gas feedpipes 4, 22, and 42 described above.

In the apparatus described above, heated gas is supplied through thefeed pipe 63 into the hot air chamber 62a, and low humidity heated gas(secondary air) can be blown from the perforated plate 61 into thewidened drying chamber 50. As a result, the particulates that spiralupward and reach the widened drying chamber 50 circle in the same placeat the bottom of the widened drying chamber 50 and the connection partunderneath because of the rapid decrease in the rate at which thespirally ascending air current ascends in this location. Theparticulates are more effectively dried (finished drying) by the thermalenergy of the ascending air current and the thermal energy of the heatedgas blown in from the perforated plate 61. Because of the decrease incentrifugal force produced from the spirally ascending air current, theparticulates which dry and become lighter once again travel in thedirection of the center and are discharged through the discharge pipe 25along with the spirally ascending air current. The particulatesdischarged from the discharge pipe 25 are separated from the air currentby the particulate separator 26 and are recovered in the form ofthoroughly dried particulates.

A fifth embodiment of the device pertaining to the present invention isdescribed below with reference to FIG. 15. In this embodiment, partswhich are the same as those in the apparatus in the first and thirdembodiments of the apparatus pertaining to the present inventiondescribed above are designated by the same symbols and will not befurther described.

The apparatus in the fifth embodiment is one which can be usedeffectively when the particulates being treated are materials withrelatively low adhesion. This apparatus has a structure in which theperforated plate 20 of the apparatus in the third embodiment describedabove is at a distance from the perforated plate 3 present underneath.The other parts are the same as in the apparatus in the third embodimentof the present invention described above.

Specifically, as shown in FIG. 15, the perforated plate 20 in which blowholes 16 are formed is arranged on the side wall of the drying chamber2b to which the particulate feed tube 2 is connected. The outerperipheral wall surface of the drying chamber 2b between the perforatedplate 3 and the peripheral surface at the bottom of the perforated plate20 is enclosed by a jacket 70, as shown in the figure, and a heat mediumsuch as hot water or heated steam is continuously supplied through apipe 72 into the space 71 formed between the jacket 70 and the outerperipheral wall surface and is discharged through a pipe 73 (the aboveis for cases of hot water, whereas in the case of heated steam, the upand down directions of the supply and discharge pipes are reversed).

In the apparatus described above, the particulates which have beensupplied through the particulate feed pipe 23 into the drying chamber 2bare blown from the blow holes 16 of the perforated plate 3 into thedrying chamber 2b, are forcibly dispersed by the heated gas forming therapid spirally ascending air current on the perforated plate 3, travelupward on the spirally ascending air current, and reach the locationwhere the perforated plate 20 described above is located.

In the location where the perforated plate 20 is set up, heated gas isintroduced through the feed pipe 22 into the hot air chamber 21a, andheated gas is blown from the perforated plate 20 into the drying chamber2b, resulting in the formation of an air current, that is, an air ring,rapidly spiraling in the peripheral direction along the perforated plate20. The air ring has the effect of impeding wet particles that spiralupward along the inner wall of the cylindrical container 1. Theparticulates that are prevented from traveling upward stay circling inthe bottom of the air ring and are effectively dried by means of thethermal energy of the heated gas and by means of the transfer of heat byconduction from the heat medium supplied into the space 71 between theouter peripheral wall surface. Because of the decrease in centrifugalforce produced from the spirally ascending air current, the particulateswhich dry and become lighter travel in the direction of the center andascend along with the spirally ascending air current through the openingformed in the center of the air ring. The rest is the same as theapparatus in the third embodiment described above.

A sixth embodiment of the device pertaining to the present invention isdescribed below with reference to FIGS. 16 and 17. In this apparatus,parts which are the same as those in the apparatus in the first andthird embodiments of the apparatus pertaining to the present inventiondescribed above are designated by the same symbols and will not befurther described.

The apparatus in the sixth embodiment is one which can be usedeffectively when the particulates being treated are materials withrelatively low adhesion, as in the case of the apparatus in the fifthembodiment described above.

This apparatus has a structure in which the feed pipe 80 through whichthe heated gas is supplied is connected in a tangential direction to thebottom 81 of the cylindrical container 1 as shown in FIG. 17, and aspirally ascending air current is formed in the cylindrical container 1.The other parts are the same as in the apparatus in the third embodimentof the present invention.

In this apparatus, heated gas fed from a tangential direction throughthe feed pipe 80 to the bottom 81 of the cylindrical container 1 formsan air current that spirally ascends inside the cylindrical container 1.

As the particulates that are introduced through the feed pipe 23 intothe cylindrical container 1 are thus dispersed and dried by the spirallyascending air current created by the heated gas, they spirally ascendalong the inner peripheral wall surface of the cylindrical container 1with the spirally ascending air current, and reach the widened dryingchamber 50.

In the widened drying chamber 50, the rate at which the spirallyascending air current ascends is dramatically reduced in the same manneras in the apparatus in the third embodiment described above, and theparticulates thus circle in place in roughly the same horizontal plane.The particulates are effectively dried by the thermal energy of theheated gas, and the particulates which subsequently dry and becomelighter travel in the direction of the center and are discharged throughthe discharge pipe 25 along with the spirally ascending air. Theparticulates discharged from the discharge pipe 25 are separated fromthe air current by the particulate separator 26 and are recovered in theform of thoroughly dried particulates.

When the feed pipe 80 through which the heated gas is supplied isconnected in a tangential direction to the bottom 81 of the cylindricalcontainer as in the apparatus described above, and a mechanism is formedto produce a spirally ascending air current inside the cylindricalcontainer 1, the apparatus may have a structure in which the feed pipethrough which the heated gas is supplied serves as a feed pipe 90doubling as a particulate feed pipe, as in the case of the seventhembodiment depicted in FIG. 18, and the particulates are supplied alongwith the heated gas through the feed pipe 90 into the cylindricalcontainer 1.

The apparatus may also have a structure in which, as in the case of theeighth embodiment of the apparatus pertaining to the present inventionshown in FIG. 19, the outlet side end of a drying pipe 101 of aconventional flash dryer is connected to the feed pipe 90 for both theheated gas and particulates. In this case, the heated gas (exhaust)passing through the conventional flash dryer 100 is converted to aspirally ascending air current in the cylindrical container 1, and theparticulates being dried as they are transported in the flow of the aircurrent are subject to the same action as that described above in thecylindrical container 1, allowing the drying performance to be enhanced.That is, the optimal particulate moisture can be lowered at the heatedgas temperature and flow rate used in the flash dryer 100, or a greateramount can be treated when the optimal temperature is the same, allowingmore efficient drying to be achieved. 102 in FIG. 19 is a beater.

Test examples confirming the effects of the various particulate dryingmethods and drying apparatus pertaining to the present invention arenoted below.

TEST EXAMPLE A

Drying MBS-Based Resin Having Moisture Content of 24% WB (mean particlediameter: 165 μm; bulk density: 0.5)

TEST EXAMPLE A1

A spirally ascending air current was formed by introducing heated gasand the particulates described above in a tangential direction into astraight pipe having an inside diameter of 250 mm and a length 5 timesgreater than the inside diameter, and the particulates were dried whileborne on the spirally ascending air current (specifically, theparticulates were dried using the apparatus depicted in FIG. 18, butwith the widened drying chamber 50 removed).

The particulate drying conditions and drying effects are given in Table1.

TEST EXAMPLE A2

A spirally ascending air current was formed by introducing heated gasfrom only the perforated plate at the bottom side wall into a straightpipe having an inside diameter of 250 mm and a length 5 times greaterthan the inside diameter, and the particulates were dried while borne onthe spirally ascending air current (specifically, the particulates weredried using the apparatus depicted in FIG. 3, while closing the valve 33located in the middle of the feed pipe 4 through which the heated gaswas introduced into the drying chamber 2a, with a flat plate placed onthe perforated plate 3).

The particulate drying conditions and drying effects are given in Table1.

TEST EXAMPLE A3

A spirally ascending air current was formed by introducing heated gasfrom the bottom side wall and bottom wall perforated plate into astraight pipe having an inside diameter of 250 mm and a length 5 timesgreater than the inside diameter, and the particulates were dried whileborne on the spirally ascending air current (specifically, theparticulates were dried using the apparatus depicted in FIG. 3).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 4:6.

The other particulate drying conditions and drying effects are given inTable 1.

TEST EXAMPLE A4

A spirally ascending air current was formed by introducing heated gasfrom the bottom side wall and bottom wall perforated plate into astraight pipe having an inside diameter of 250 mm and a length 5 timesgreater than the inside diameter, and the particulates were dried whileborne on the spirally ascending air current (specifically, theparticulates were dried using the apparatus depicted in FIG. 3).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 7:3.

The other particulate drying conditions and drying effects are given inTable 1.

TEST EXAMPLE A5

A spirally ascending air current was formed by introducing heated gasfrom the bottom side wall and bottom wall perforated plate into acontainer having a widened component with an inside diameter of 350 mmand a length of 250 mm midway (at a location 750 mm from the bottomwall) in a straight pipe having an inside diameter of 250 mm and alength 5 times greater than the inside diameter, and the particulateswere dried while borne on the spirally ascending air current(specifically, the particulates were dried using the apparatus depictedin FIG. 13).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 7:3.

The other particulate drying conditions and drying effects are given inTable 1.

                                      TABLE 1                                     __________________________________________________________________________                                        Mfg.                                      Particulate                                                                             Heated gas             Solid                                                                            product                                   amount    Superficial        Outlet                                                                            air                                                                              moisture                                  fed       velocity                                                                           Flow Rate                                                                          Weight                                                                            Inlet temp.                                                                        temp.                                                                             ratio                                                                            content                                   (kg/hr)   (m/sec)                                                                            (m.sup.3 /min)                                                                     (kg/hr)                                                                           (° C.)                                                                      (° C.)                                                                     (--)                                                                             (% WB)                                                                             Adhesion                             __________________________________________________________________________    Test 50   6.0  16.6 890 110  83  0.056                                                                            --   X (note 1)                           Example                                                                       A1                                                                            Test 50   6.0  16.6 890 110  83  0.056                                                                            6.5  Δ (note 2)                     Example                                                                       A2                                                                            Test 50   6.0  16.6 890 110  83  0.056                                                                            6.5  ◯ (note 3)               Example                                                                       A3                                                                            Test 50   6.0  16.6 890 110  83  0.056                                                                            6.5  ⊚ (note 4)            Example                                                                       A4                                                                            Test 50   6.0  16.6 890 110  83  0.056                                                                            6.5  ⊚                     Example                                                                       A5                                                                            __________________________________________________________________________     Note 1) Particulates adhered to part of the side surface of the container     immediately after operations commenced and spread over the entire side        surface as operations continued, resulting in an abundance of particulate     remaining on the bottom surface.                                              Note 2) Coneshaped accumulation was noted in the center of the bottom         surface.                                                                      Note 3) Slight adhesion was noted on some of the side surface, but this       did not increase.                                                             Note 4) There was no adhesion.                                           

It could be confirmed on the basis of the Test Examples A above that itis advantageous to introduce heated gas from both the bottom side walland bottom wall into the cylindrical container and to thus form aspirally ascending air current so as to dry wet particulates becausethere is less particulate adhesion and accumulation. It was alsoconfirmed that it is more advantageous to introduce a greater amount ofheated gas from the bottom side wall than from the bottom wall whenheated gases are introduced from the bottom side wall and bottom wallperforated plate into the cylindrical container because there is lessparticulate adhesion and accumulation.

When the particulates described above were dried without the use of adispersing device for the treated material in a conventional flash dryer(an apparatus in which particulates are dried simply by forming anascending air current using heated gas in a straight pipe) for the sakeof comparison, the particulates turned into wet lumps and thus could notbe borne on the ascending air current, with many falling to the bottomof the dryer. Many of the particulates that were borne on the aircurrent adhered to the vent at the top. The final product had a moisturecontent of 15% WB.

Test B

Drying MBS-Based Resin Having Moisture Content of 6% WB (specifically,dry particulates obtained in Test Example A5 above)

TEST EXAMPLE B1

A spirally ascending air current was formed by introducing heated gasand the particulates described above in a tangential direction into astraight pipe having an inside diameter of 250 mm and a length 5 timesgreater than the inside diameter, and the particulates were dried whileborne on the spirally ascending air current (specifically, theparticulates were dried using the apparatus depicted in FIG. 18, butwith the widened drying chamber 50 removed).

The particulate drying conditions and drying effects are given in Table2.

TEST EXAMPLE B2

A spirally ascending air current was formed by introducing heated gasfrom the bottom side wall and bottom wall perforated plate into astraight pipe having an inside diameter of 250 mm and a length 5 timesgreater than the inside diameter, and the particulates were dried whileborne on the spirally ascending air current (specifically, theparticulates were dried using the apparatus depicted in FIG. 3).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 5:5.

The other particulate drying conditions and drying effects are given inTable 2.

TEST EXAMPLE B3

A spirally ascending air current was formed by introducing heated gasfrom the bottom side wall and bottom wall perforated plate into acontainer having a wider component with an inside diameter of 300 mm anda length of 250 mm midway (at a location 750 mm from the bottom wall) ina straight pipe having an inside diameter of 250 mm and a length 5 timesgreater than the inside diameter, and the particulates were dried whileborne on the spirally ascending air current (specifically, theparticulates were dried using the apparatus depicted in FIG. 13).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 5:5.

The other particulate drying conditions and drying effects are given inTable 2.

TEST EXAMPLE B4

A spirally ascending air current was formed by introducing heated gas ina tangential direction into a container having a widened component withan inside diameter of 350 mm and a length of 250 mm midway (at alocation 750 mm from the bottom wall) in a straight pipe having aninside diameter of 250 mm and a length 5 times greater than the insidediameter, and the particulates were dried while borne on the spirallyascending air current (specifically, the particulates were dried usingthe apparatus depicted in FIG. 18).

The particulate drying conditions and drying effects are given in Table2.

TEST EXAMPLE B5

A spirally ascending air current was formed by introducing heated gasfrom the bottom side wall and bottom wall perforated plate into acontainer having a widened component with an inside diameter of 350 mmand a length of 250 mm midway (at a location 750 mm from the bottomwall) in a straight pipe having an inside diameter of 250 mm and alength 5 times greater than the inside diameter, and the particulateswere dried while borne on the spirally ascending air current(specifically, the particulates were dried using the apparatus depictedin FIG. 13).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 5:5.

The other particulate drying conditions and drying effects are given inTable 2.

TEST EXAMPLE B6

A spirally ascending air current was formed by using 95° C. hot water toheat the outer peripheral wall surfaces of a container having a widenedcomponent with an inside diameter of 350 mm and a length of 250 mmmidway (at a location 750 mm from the bottom wall) in a straight pipehaving an inside diameter of 250 mm and a length 5 times greater thanthe inside diameter and by introducing heated gas from the bottom sidewall and bottom wall perforated plate into the above container, and theparticulates were dried while borne on the spirally ascending aircurrent (specifically, the particulates were dried using the apparatusdepicted in FIG. 13, as the 95° C. hot water was supplied into ajacket).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b and 5:5.

The other particulate drying conditions and drying effects are given inTable 2.

                                      TABLE 2                                     __________________________________________________________________________                                        Mfg.                                      Particulate                                                                             Heated gas             Solid                                                                            product                                   amount    Superficial        Outlet                                                                            air                                                                              moisture                                  fed       velocity                                                                           Flow Rate                                                                          Weight                                                                            Inlet temp.                                                                        temp.                                                                             ratio                                                                            content                                   (kg/hr)   (m/sec)                                                                            (m.sup.3 /min)                                                                     (kg/hr)                                                                           (° C.)                                                                      (° C.)                                                                     (--)                                                                             (% WB)                                    __________________________________________________________________________    Test 50   6.0  16.6 890 110  80  0.056                                                                            2.2                                       Example                                                                       B1                                                                            Test 50   6.0  16.6 890 110  79  0.056                                                                            1.9                                       Example                                                                       B2                                                                            Test 50   6.0  16.6 890 110  75  0.056                                                                            0.67                                      Example                                                                       B3                                                                            Test 50   6.0  16.6 890 110  75  0.056                                                                            0.48                                      Example                                                                       B4                                                                            Test 50   6.0  16.6 890 110  75  0.056                                                                            0.46                                      Example                                                                       B5                                                                            Test 50   6.0  16.6 890 110  75  0.056                                                                            0.40                                      Example                                                                       B6                                                                            __________________________________________________________________________     Note) No particulate adhesion or accumulation was noted in the apparatus      in any of the test examples.                                             

It could be confirmed on the basis of the Test Examples B above that noparticulates adhered or accumulated when a spirally ascending aircurrent was formed by introducing heated gas in a tangential directioninto the cylindrical container to dry particulates that were already dryto a certain extent. It could also be confirmed that expanding thespiral diameter of the spirally ascending air current in the middle orheating the outer peripheral surface of the cylindrical container wasextremely effective in improving the dry state of the particulates.

When the particulates described above were dried without the use of adispersing device for the treated material in a conventional flash dryerfor the sake of comparison, the final product had a moisture content of4.0% WB. Because of the low initial moisture content, no particulateadhesion or accumulation inside the apparatus was observed.

TEST EXAMPLE C

Drying PVC (Polyvinyl Chloride) Resin Powder Having Moisture Content of23% WB (mean particle diameter: 135 μm)

TEST EXAMPLE C1

A spirally ascending air current was formed by introducing heated gasand the particulates described above in a tangential direction into astraight pipe having an inside diameter of 350 mm and a length 5 timesgreater than the inside diameter, and the particulates were dried whileborne on the spirally ascending air current (specifically, theparticulates were dried using the apparatus depicted in FIG. 3).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 7:3.

The other particulate drying conditions and drying effects are given inTable 3.

TEST EXAMPLE C2

A spirally ascending air current was formed by introducing heated gasfrom the bottom side wall and bottom wall perforated plate into acontainer having a widened component with an inside diameter of 430 mmand a length of 350 mm midway (at a location 1050 mm from the bottomwall) in a straight pipe having an inside diameter of 350 mm and alength 5 times greater than the inside diameter, and the particulateswere dried while borne on the spirally ascending air current(specifically, the particulates were dried using the apparatus depictedin FIG. 13).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 7:3.

The other particulate drying conditions and drying effects are given inTable 3.

TEST EXAMPLE C3

A spirally ascending air current was formed by introducing heated gasfrom the bottom side wall and bottom wall perforated plate into acontainer, which had a widened component with an inside diameter of 430mm and a length of 350 mm as well as a perforated plate provided on theside surface of the wider part, midway (at a location 1050 mm from thebottom wall) in a straight pipe having an inside diameter of 350 mm anda length 5 times greater than the inside diameter, and the particulateswere dried while borne on the spirally ascending air current as heatedgas (secondary air) was also introduced from the perforated plate on theside wall of the wider part (specifically, the particulates were driedusing the apparatus depicted in FIG. 14).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 7:3, andthe amount of secondary air was 15% of the heated gas supplied form thebottom side wall and bottom wall perforated plate.

The other particulate drying conditions and drying effects are given inTable 3.

TEST EXAMPLE C4

A spirally ascending air current was formed by introducing heated gasfrom the bottom side wall and bottom wall perforated plate into acontainer, which had a perforated plate on the entire periphery of theside wall at a breadth of 40 mm in the heightwise direction, midway (ata location 1050 mm from the bottom wall) in a straight pipe having aninside diameter of 350 mm and a length 5 times greater than the insidediameter, and the particulates were dried while borne on the spirallyascending air current as heated gas (for an air ring) was alsointroduced from the perforated plate on the entire periphery of the sidewall midway in the straight pipe (specifically, the particulates weredried using the apparatus depicted in FIG. 10).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 7:3, andthe amount of heated gas for the air ring was 15% of the heated gassupplied form the bottom side wall and bottom wall perforated plate.

The other particulate drying conditions and drying effects are given inTable 3.

TEST EXAMPLE C5

A spirally ascending air current was formed by using heated steam with apressure of 1 kg/cm² -G to heat the outer peripheral wall surfacebetween the bottom side wall perforated plate and bottom wall of acontainer which was a straight pipe having an inside diameter of 350 mmand a length 5 times greater than the inside diameter and which had abottom side wall perforated plate located 175 mm from the bottom wall,and by introducing heated gas from the bottom side wall and bottom wallperforated plate into the container, and the particulates were driedwhile borne on the spirally ascending air current (specifically, theparticulates were dried using the apparatus depicted in FIG. 15, butwith the widened drying chamber 50 removed).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 8:2.

The other particulate drying conditions and drying effects are given inTable 3.

TEST EXAMPLE C6

A spirally ascending air current was formed by using heated steam with apressure of 1 kg/cm² -G to heat the outer peripheral wall surfacebetween the bottom side wall perforated plate and bottom wall of acontainer which had a widened part with an inside diameter of 430 mm anda length of 350 mm and which had a bottom side wall perforated platelocated 175 mm from the bottom wall midway (at a location 1050 mm fromthe bottom wall) in a straight pipe having an inside diameter of 350 mmand a length 5 times greater than the inside diameter, and byintroducing heated gas from the bottom side wall and bottom wallperforated plate into the container, and the particulates were driedwhile borne on the spirally ascending air current (specifically, theparticulates were dried using the apparatus depicted in FIG. 15).

The ratio of the amount of heated gas supplied from the bottom side walland bottom wall perforated plate into the drying chamber 2b was 8:2.

The other particulate drying conditions and drying effects are given inTable 3.

                                      TABLE 3                                     __________________________________________________________________________                                        Mfg.                                      Particulate                                                                             Heated gas             Solid                                                                            product                                   amount    Superficial        Outlet                                                                            air                                                                              moisture                                  fed       velocity                                                                           Flow Rate                                                                          Weight                                                                            Inlet temp.                                                                        temp.                                                                             ratio                                                                            content                                   (kg/hr)   (m/sec)                                                                            (m.sup.3 /min)                                                                     (kg/hr)                                                                           (° C.)                                                                      (° C.)                                                                     (--)                                                                             (% WB)                                    __________________________________________________________________________    Test 150  7.0  40.4 2063                                                                              120  73  0.073                                                                            3.0                                       Example                                                                       C1                                                                            Test 220  7.0  40.4 2063                                                                              120  62  0.107                                                                            0.8                                       Example                                                                       C2                                                                            Test 220  7.0  40.4 2063                                                                              120  62  0.093                                                                            0.5                                       Example                                                                       C3                                                                            Test 220  7.0  40.4 2063                                                                              120  59  0.093                                                                            1.1                                       Example                                                                       C4                                                                            Test 210  6.1  35.0 1829                                                                              120  71  0.115                                                                            0.3                                       Example                                                                       C5                                                                            Test 210  6.1  35.0 1829                                                                              120  70  0.115                                                                            0.2                                       Example                                                                       C6                                                                            __________________________________________________________________________     Note) In Test Examples C1 and C2, additional heated gas was supplied at       309 (kg/hr) (included in calculation of solidair ratio).                 

It could be confirmed on the basis of Test Examples C that theparticulate drying state was improved in an extremely effective mannerwhen the spiral diameter of the spirally ascending air current in thecylindrical container was widened in the middle, and heated gas wasintroduced into the part with the widened spiral diameter, or when arapidly spiraling air current, that is, an air ring, was formed at alocation at any height in the cylindrical container, and the outerperipheral surface of the cylindrical container was heated at a locationbelow the location where the air ring was formed.

TEST EXAMPLE D

Drying PVC (Polyvinyl Chloride) Resin Powder Having Moisture Content of23% WB (mean particle diameter: 130 μm)

TEST EXAMPLE D1

The particulates described above were dried using a conventional flashdryer which had an inside diameter of 145 mm, a length of 14.5 m, andcurved parts in three locations (specifically, the particulates weredried using the apparatus in FIG. 19, except that the cylindricalcontainer 1 was removed).

The other particulate drying conditions and drying results are shown inTable 4.

TEST EXAMPLE D2

The particulates described above were dried using a device in which theoutlet side end of the drying pipe of a conventional flash dryer whichhad an inside diameter of 145 mm, a length of 14.5 m, and curved partsin three locations was connected in a tangential direction to the bottomof a cylindrical container having an inside diameter of 250 mm and alength 5 times greater than the inside diameter (specifically, theparticulates were dried using the apparatus in FIG. 19, except that thewidened drying chamber 50 was removed).

The other particulate drying conditions and drying results are shown inTable 4.

TEST EXAMPLE D3

The particulates described above were dried using a device in which theoutlet side end of the drying pipe of a conventional flash dryer whichhad an inside diameter of 145 mm, a length of 14.5 m, and curved partsin three locations was connected in a tangential direction to the bottomof a container in which a widened part with an inside diameter of 350 mmand a length of 250 mm was provided midway (at a location 750 mm fromthe bottom wall) in a cylindrical container having an inside diameter of250 mm and a length 5 times greater than the inside diameter(specifically, the particulates were dried using the apparatus in FIG.19).

The other particulate drying conditions and drying results are shown inTable 4.

                                      TABLE 4                                     __________________________________________________________________________                                        Mfg.                                      Particulate                                                                             Heated gas             Solid                                                                            product                                   amount    Superficial        Outlet                                                                            air                                                                              moisture                                  fed       velocity                                                                           Flow Rate                                                                          Weight                                                                            Inlet temp.                                                                        temp.                                                                             ratio                                                                            content                                   (kg/hr)   (m/sec)                                                                            (m.sup.3 /min)                                                                     (kg/hr)                                                                           (° C.)                                                                      (° C.)                                                                     (--)                                                                             (% WB)                                    __________________________________________________________________________    Test 72   19.0 18.8 987 120  66  0.073                                                                            2.9                                       Example                                                                       D1                                                                            Test 72   19.0 18.8 987 120  64  0.073                                                                            0.7                                       Example                                                                       D2                                                                            Test 72   19.0 18.8 987 120  63  0.073                                                                            0.3                                       Example                                                                       D3                                                                            __________________________________________________________________________     Note) The superficial velocity was the velocity of the heated gas in the      flash drying. In Test Example D1, the outlet temperature was the inlet        temperature of the particulate separator.                                

It could be confirmed on the basis of the Test Examples D above that thedry state of the particulates could be further improved at the heatedgas temperature and flow rate used in the flash dryer when the outletside end of the drying pipe of the conventional flash dryer wasconnected in a tangential direction to the bottom of the cylindricalcontainer, and a spirally ascending air current was formed inside thecylindrical container using the drying method and apparatus pertainingto the present invention, so as to further dry particulates which hadalready been dried by a flash dryer.

INDUSTRIAL APPLICABILITY

The particulate drying method and apparatus pertaining to the presentinvention are a particulate drying method and apparatus which canimprove the dry state of particulates by dispersing particulates in adryer and by prolonging the residence time of the particulates whileretaining the advantages of conventional flash dryers. Particulateswhich can be treated by the particulate drying method and apparatuspertaining to the present invention include various inorganic materials,organic materials, metals, and polymers. When the particulates beingtreated contain a variety of organic solvents, or when there is a dangerof ignition or explosion due to the physical properties or the like ofthe particulates, an inert gas such as nitrogen gas should be usedinstead of air as the heated gas.

What is claimed is:
 1. A method for drying particulates in a spirallyascending air current inside a cylindrical container having an internalspace, the internal space having a horizontal cross section in the formof a concentric circle along a length of the internal space, the methodcomprising:introducing heated gas in one tangential direction from aperiphery of a bottom side wall of the cylindrical container, so as toform the spirally ascending air current in the cylindrical container,and introducing particulates to be dried into the internal space of thecylindrical container so that the particulates float in the spirallyascending air current in the cylindrical container.
 2. The method fordrying particulates according to claim 1, wherein the heated gas isintroduced adjacent a bottom wall of the cylindrical container in acircumferential direction concentric with the cylindrical containertogether with the introduction of the heated gas in one tangentialdirection from the periphery of the bottom side wall of the cylindricalcontainer, so as to form the spirally ascending air current in thecylindrical container.
 3. The method for drying particulates accordingto claim 2, wherein an amount of the heated gas introduced from theperiphery of the bottom side wall of the cylindrical container is equalto or greater than that of the heated gas introduced adjacent the bottomwall of the cylindrical container.
 4. The method for drying particulatesaccording to claim 1, wherein the cylindrical container is heated fromthe outer peripheral surface thereof.
 5. The method for dryingparticulates according to claim 1, wherein the cylindrical container isconstructed so as to be axially dividable.
 6. The method for dryingparticulates according to claim 1, wherein the heated gas is alsointroduced in the same direction as spiraling direction of the spirallyascending air current at a location above the bottom wall of thecylindrical container, so as to form an air ring at the location.
 7. Themethod for drying particulates according to claim 1, wherein a diameterof a spiral of the spirally ascending air current formed in thecylindrical container is wider in a middle of the spirally ascending aircurrent.
 8. The method for drying particulates according to claim 1,wherein a diameter of a spiral of the spirally ascending air currentformed in the cylindrical container is wider in a middle of the spirallyascending air current, and the cylindrical container is heated from theouter peripheral surface at a location where the spiral diameter iswider.
 9. The method for drying particulates according to claim 1,wherein a diameter of a spiral of the spirally ascending air currentformed in the cylindrical container is wider in a middle of the spirallyascending air current, and the heated gas is also introduced in the samedirection as the spiraling direction of the spirally ascending aircurrent at a location where the spiral diameter is wider.
 10. The methodfor drying particulates according to claim 1, wherein the heated gas isalso introduced in the same direction as the spiraling direction of thespirally ascending air current at a location in the cylindricalcontainer, so as to form an air ring at the location, and thecylindrical container is heated from the outer peripheral surface at alocation below where the air ring has been formed.
 11. An apparatus fordrying particulates comprising:a cylindrical container having aninternal space, the internal space having a length with a horizontalcross section in the form of a concentric circle; particulate and heatedgas feed pipes which are connected to a bottom of the cylindricalcontainer; a spiraling mechanism for converting the heated gasintroduced from the feed pipe into a spirally ascending air currentinside the cylindrical container; and a particulate and heated gasexhaust pipe which is connected to the top of the cylindrical container,wherein a periphery of the bottom side wall of the cylindrical containeris made of a perforated plate having a plurality of blow holes arrangedso that openings thereof face in one tangential direction of thecylindrical container, a periphery of the perforated plate is enclosedby a bottom container, and the heated gas feed pipe is connected to thebottom container, thereby constituting the spiraling mechanism.
 12. Theapparatus for drying particulates according to claim 11, wherein theentire surface of the bottom wall of the cylindrical container is madeof a perforated plate having a plurality of blow holes arranged withopenings facing in one circumferential direction concentric with thecylindrical container.
 13. The apparatus for drying particulatesaccording to claim 11, wherein the heated gas feed pipe is connected tothe bottom container enclosing the perforated plate in the tangentialdirection of the openings of the blow holes in the perforated plateface.
 14. The apparatus for drying particulates according to claim 11,having a construction so that the outer peripheral wall surface of thecylindrical container is enclosed by a jacket, and a heat medium issupplied into the space formed between the jacket and the outerperipheral wall surface of the cylindrical container.
 15. The apparatusfor drying particulates according to claim 11, having a construction sothat the entire periphery of the side wall at a location above thebottom side wall of the cylindrical container is made of a perforatedside plate having a plurality of blow holes with openings facing in thesame direction as the spiraling direction of the spirally ascending aircurrent formed in the cylindrical container by the spiraling mechanism,the periphery of the perforated side plate is enclosed by a sidecontainer, and the heated gas feed pipe is connected to the sidecontainer, thereby forming an air ring at the location on thecylindrical container.
 16. The apparatus for drying particulatesaccording to claim 11, wherein the cylindrical container is acylindrical container having an internal space with a middle sectionarranged between two end sections along an axis of the cylindricalcontainer such that a horizontal cross section is in the form ofconcentric circles that are wider in the middle section than in the twoend sections.
 17. The apparatus for drying particulates according toclaim 16, wherein an area of the horizontal cross section of theinternal space at the middle section is 1.1 to 3.0 times wider than atthe two end sections.
 18. The apparatus for drying particulatesaccording to claim 11, wherein the cylindrical container has an internalspace with a middle section arranged between two end sections along anaxis of the cylindrical container such that a horizontal cross sectionis in the form of concentric circles that are wider in the middlesection than in the two end sections, the outer peripheral wall surfaceof the cylindrical container at the middle section where the internalspace is wider is enclosed by a jacket, and a heat medium is supplied ina space formed between the jacket and the outer peripheral wall surfaceof the cylindrical container.
 19. The apparatus for drying particulatesaccording to claim 11, wherein the cylindrical container is acylindrical container having an internal space with a middle sectionarranged between two end sections along an axis of the cylindricalcontainer such that a horizontal cross section is in the form ofconcentric circles that are wider in the middle section than in the twoend sections, the side wall of the cylindrical container at the partwhere the internal space is wider is made of a perforated side platehaving a plurality of blow holes arranged so that openings thereof facein the same direction as the spiraling direction of the spirallyascending air current formed in the cylindrical container by thespiraling mechanism, the periphery of the perforated side plate isenclosed by a side container, and the heated gas feed pipe is connectedto the side container.
 20. The apparatus for drying particulatesaccording to claim 11, having a construction so that the entireperiphery of the side wall at a location above the bottom side wall ofthe cylindrical container is made of a perforated side plate having aplurality of blow holes with openings facing in the same direction asthe spiraling direction of the spirally ascending air current formed inthe cylindrical container by the spiraling mechanism, the periphery ofthe perforated plate is enclosed by a side container, and the heated gasfeed pipe is connected to the side container, thereby forming an airring at the location on the cylindrical container, while the outerperipheral wall surface of the cylindrical container at a location belowwhere the air ring has been formed is enclosed by a jacket, and a heatmedium is supplied in the space formed between the jacket and the outerperipheral wall surface of the cylindrical container.